✅ check coerce is called only when necessary

README.md

@@ -52,6 +52,11 @@ VueCoerceProps will inject a computed property named `$coerced` containing every
 </p>
 ```
 
+## FAQ
+
+* Q: Why not passing component props as second argument?
+  A: That would make every coerce value depend on every prop. At the end `$coerced` is just a computed property
+
 ## License
 
 [MIT](http://opensource.org/licenses/MIT)

test/index.spec.js

@@ -75,4 +75,39 @@ describe('VueCoerceProps', () => {
     }).not.toThrow()
     expect(wrapper.vm.$coerced.other).toBe('Hello Ed!')
   })
+
+  test('calls coerce function only if props change', () => {
+    const spy = jest.fn()
+    spy.mockResolvedValue('hey')
+    wrapper = mount(
+      {
+        mixins: [mixin],
+        render: h => h(),
+        props: {
+          value: String,
+          trimmed: {
+            type: String,
+            coerce: spy,
+          },
+        },
+      },
+      {
+        propsData: {
+          value: 'Hi',
+          trimmed: 'hey',
+        },
+      }
+    )
+    // trigger a call
+    expect(wrapper.vm.$coerced).toBeDefined()
+    expect(spy).toHaveBeenCalledTimes(1)
+
+    wrapper.setProps({ value: 'hi2' })
+    expect(wrapper.vm.$coerced).toBeDefined()
+    expect(spy).toHaveBeenCalledTimes(1)
+
+    wrapper.setProps({ trimmed: 'hi3' })
+    expect(wrapper.vm.$coerced).toBeDefined()
+    expect(spy).toHaveBeenCalledTimes(2)
+  })
 })